Traditional music existed perfectly well for centuries without requring "someone from outside the class or culture to 'save' the people from themselves". It was only when it ceased to be relevant to the communities it had formerly served that the question of preservation arose. Even then, the impetus was not solely from outside those communities - the value of the traditional songs was often recognised by those within the tradition who did what they could to preserve the songs - Walter Pardon and Bob Copper come to mind.

It's a strange sort of cultural relativism which says that only the original communities have the right to decide what happens to these songs, and that if they reject them then no one else should step in to preserve them.

The fact is, there is still a community for whom these songs are relevant. It's a very different, self-conscious community which probably approaches the music differently from the original singers, but it exists nonetheless, and the music continues to live and evolve. I believe we are continuing a tradition, albeit differently than before. However let's not pretend it's any longer the "Voice of the People" - the People have moved on to other things.